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The hugely serious Meltdown bug, present in systems with Intel and AMD processors, still shows no sign of being fully solved.

If you have an affected processor in your PC, you should be worried. The bug allows a hacker to exploit a flaw in the design of the processor to run their own code on your system.

People can't easily swap the processor in their PC, and usually need to change the motherboard and memory too. So, Microsoft stepped in and issued patches for Windows in January and February which were designed to block hackers from making use of the bug.

However, it turns out that Microsoft's fixes might have made PCs running Windows 7 less secure, rather than more secure.

According to security researchers, Ulf Frisk, the fixes from Microsoft made a crucial kernel memory table readable and writable for normal user processes.

This means that any malware code that manages to run on your system, even without administrative privileges, can access the full system memory, gain administrator privileges and insert its own code into protected areas of memory. Once it has done this, it has full control of your system.

Malware could also use the bug in Microsoft's fix to read passwords, and other sensitive data, from protected areas of memory.

Although the problem with Microsoft's fix affects all versions of Windows, from Windows 7 to Windows 10, Windows 8.1 and 10 have extra security features that protect the memory contents.

Unfortunately, these features are not present on Windows 7, so the fix leaves those systems wide open to attack.

Microsoft have managed to act on the tip off and have just released a new fix to cure the problem they created.

If you have Windows 7, you need to make sure that this fix is installed immediately. Unlike Windows 10, it is possible to configure Windows 7 to disable automatic updates, so you are not guaranteed to have it.

To check if there are any updates waiting to be installed for your system, click on Start > Control Panel > Windows Update.

Click on the Check now button to search for available updates and install any that are found.